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List of boundary conditions with specifications
| Element: | Type of boundary conditions | Conditions related to the conservation of momentum | Thermal conditions |
|---|---|---|---|
| Nostrils | Mass-flow inlet | Mass flux defined by the user | Temperature defined by the user, T = 307 K |
| Face shield surface | Wall | Standard fixed walls | Zero heat flux |
| Fabric mask | Porous Jump | Porous material | Zero heat flux |
| Body surface | Wall | Standard fixed walls | Heat flux 40 W/m2 |
| The outer surface of the numerical domain | Pressure-outlet | Standard conditions | T = 293 K |
Grid parameters used for grid independence study
| Mesh: | 1.1 | 1.2 | 1.3 | 1.4 |
| Element Size [mm]: | 20 | 15.4 | 11.5 | 8.8 |
| Sizing [mm]: | 5 | 3.8 | 2.9 | 2.2 |
| Number of elements: | 887 932 | 1 643 675 | 2 886 498 | 5 251 038 |
List of parameters describing the quality of meshes
| Model | Number of elements | Average skewness | Average orthogonal quality |
|---|---|---|---|
| Reference model without PPE | 2 485 096 | 0.181 | 0.817 |
| Model with shield covering nose and mouth | 2 637 907 | 0.183 | 0.814 |
| Model with face shield, 15 mm far from face | 2 779 952 | 0.185 | 0.812 |
| Model with face shield, 40 mm far from face | 2 811 042 | 0.186 | 0.811 |
| Model with a fabric mask | 907 944 | 0 (skewness parameter is not applicable for polyhedral mashes) | 0.96526 |
Results of the mesh independence study
| Mesh | Number of cells, Millions | Mesh refinement ratio | Solution, ppm | Observed discretisation order | GCI |
|---|---|---|---|---|---|
| 1.1 | 0.888 | - | 725.5 | - | - |
| 1.2 | 1.644 | 0.81 | 750.0 | - | 0.123 |
| 1.3 | 2.886 | 0.83 | 767.7 | 1.63 | 0.086 |
| 1.4 | 5.251 | 0.82 | 784.0 | - | 0.077 |